1. Field of the Invention
The present invention relates to a cooling arrangement for the gun barrels of firearms, in particular automatic firearms and high-performance machine cannons, which includes radially outwardly directed cooling passageways between the individual projectile chambers provided in the drum in the region of the end portion of the gun barrel axially adjoining the drum, and which are connected with a main passageway in the hollow-bored longitudinal barrel axis for the central cooling medium infeed.
As a rule, difficult conditions are encountered by the gun barrel of an automatic firearm or a high-performance machine cannon during operational use thereof. In general, when there are to be fired only short firing bursts which are controlled by a firing count limiter, then there has also been ascertained that, for instance, the pilot of a combat aircraft must have the capability at any given instance of firing the entire ammunition supply in a single firing burst. Thereby there must be met at least the demands that towards the end of the firing burst there will not be endangered the operating personnel, and the aircraft encounters damage to its fuselage surfaces through shortened self-destructing periods, through rapidly reducing projectile speeds and through cross impacting projectiles.
Furthermore, there may not occur any gas backup and no duds may be encountered up to about 100 to 200 meters ahead of the mouth of the gun barrel. Furthermore, it is also important that the target sighting be adequately maintained.
2. Discussion of the Prior Art
In the mentioned high-performance firearms, which fire highly sophisticated ammunition, the extensive wear of the gun barrel can be always traced back in that the surface heat is not sufficiently rapidly dissipated. The rapid successively applied heat buildup during the firing burst produces surface stresses and material transformations. Due to the fluttering of the projectiles in the gun barrel the flutings are deformed and this leads to a removal of material through the guide band of the projectiles. In order to increase the life expectancy of the gun barrels, it has been proposed to conduct a cooling liquid about the gun barrel. Thus, for example, in U.S. Pat. No. 2,801,575 cooling water is conveyed through a main passageway to a battery of cooling conduits which extend radially from the drum axle, which are presently introduced into the drum between the projectile chambers and which connect with a cooling passageway presently extending in parallel with the drum axle. The heated cooling water is again discharged at the rearward drum end through a passageway system. In order to achieve a sufficient reduction in the heat through this indirect cooling, it is necessary to arrange a large number of cooling passageways within the drum. The entire cooling passageway system becomes thereby extremely complex, without leading to a desired optimum extent of cooling in precisely the bore of the barrel at the rearward portion of the gun barrel. Hereby, if at all possible, there should not be exceeded a temperature of about 400.degree. C. on the bore surface of the gun barrel. In accordance with the proposal of this U.S. patent, the heat of vaporization is not employed.